Electrical-circuit protector.



No. 800,833. PATENTBD OCT. 8, 1905.

C. A. ROLFE.

ELECTRICAL CIRCUIT PROTECTOR. APPLICATION FILED JULY 28,1904.

I I .lll 115 UNITED STATES PATENT` OFFICE.

CHARLES A. ROLFE, OF ADRIAN, MICHIGAN, ASSIGNOR TO ROLFE ELECTRIC COMPANY, OF ROCHESTER, NEINT YORK, A CORPORA- TION OF NEW YORK.

ELECTRICAL-CIRCUIT PROTECTOR.

'Specicaton of Letters Patent.

Patented Oct. 3, 1905.

To n/ZZ whom, it may concern,.-

Be it known that I, CHARLES A. RoLFn, a citizen of the United States, residing at Ad rian, in the county of Lenawee and State of Michigan, have invented a certain new and useful Improvement in Electrical -Circuit Protectors, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to electrical-circuit protectors for protecting electrical circuits containing the more delicate instruments* such, for example, as telephones, fire-alarm apparatus, and the' like-from the unduly strong and dangerous currents from power, lighting, and similar circuits and especially from excessive currents which rise in strength slowly, commonly known. as sneak currents.

Prominent objects of the invention are to provide a device of this character which will not require repair or replacement in whole or in part after operation and which will operate with accuracy and effectiveness, to simplify the construction of the same and make such construction practical and durable, and to secure the foregoing and other desirable results in a simple and expeditious manner.

In the accompanying drawings, Figure 1 is a side elevation of an electrical-circuit protector embodying my present invention. Fig. 2is a longitudinal section of the upper portion of the same on an enlarged scale. Fig. 3 is a transverse section taken on line 3 3 in Fig. 2. Figs. 1 and 5 are views of an interior portion of the device in different positions.

Referring first to Fig. 1, I have shown for carrying out my invention a device comprising a base 1, made of insulating materialsuch as wood, porcelain, or the like-a pair of line-springs 2 3, secured to and rising from the base 1, and a removable and replaceable device 4, which I shall term a heat-cartridge, supported and held in position by the line-springs 2 and 3. The base 1 is provided with binding-posts 5 6, by which the wires of the circuit to be protected can be attached and connected with the line-springs 2 and 3.

The heat cartridge 4. conveniently comprises a tube 7.l made of insulating materialsuch as hard rubber, ber, or the like-and made with a large bore 8, open at one end, and

a small bore 9, opening at the other end. A core conveniently consisting' of a metallic hood or cap 10 and a block 11 of insulating material, preferably fiber, is fitted within the larger bore 8. The cap 10 is provided with a spindle 12, which extends out through the small bore 9 and projects beyond the end of the tube 7 and has its outer end screw-threaded, and upon this screw-threaded end is fitted a metallic head or terminal 21, which incloses the end of the tube 7 and has an annular groove 22. A bobbin 13 for a coil of wire 111 is fitted to the outer end of the block 11, as by means of a threaded shank 15, screwed into said block 11. The coil 14: has one of its ends connected to the cap 10, as shown in Fig, 5, and the other end connected with the bobbin 13. The bobbin 13 is desirably made of metal, and its outer flange 16 is substantially the size of the bore 8, so as to close the end of said bore, as well shown in Fig. 2. A pair of ears 17 17, Fig. 5, are provided on the bobbin 13, being conveniently made integral therewith. A trigger 18 is located with its middle portion between the ears 17 17 and pivoted at its middle point by means of a pin 19, passed through said ears. A small quantity of solder 20, fusible or softenable on a moderate excess of temperature, is placed bctween the ears 17 17, so as to partially or nearly fill the space between the same, and thus come in contact with and substantially inclose the portion of the trigger 18 which lies between said ears. A metallic collar 23 is fitted over the hollow end of the tube 7,

this collar 23 being substantially the size and shape of the portion of the head 21 which incloses the other end of the tube 7, so that the cartridge presents a symmetrical appearance of having two metallic bands upon it-'one at each end.

The line-springs 2and 3 are forked at their upper ends, and the cartridge above described is fitted upon and held in place by said linesprings by passing the ends of the cartridge into the forked portions of the line-springs, the ears 17 17 entering the forked end of the line-spring 3 and the reduced portion of the head 21, formed by the annular groove 22, fitting into the forked portion of the linespring 2. When so fitted in position, the linesprings 2 and. 3 will beheld under restraintthat is, their free or upper ends will tend to IOO spring apart, but will be prevented from so doing b y the heat-cartridge 4, the strain being received directly from the line-springs by the head 21 and the trigger 18, whose lower end is in contact with the line-spring 8, as well shown in Figs. 1 and 2.. When the device is set, the trigger 18 is in an inclined position, with its lower end in an inward position, as shown in Figs. 1, 2, and 4. As thus arranged and with the heat-cartridge supported by the line-springs and in turn holding them in restraint, the circuit connections are from one side of the circuit to the line-spring 2, from this spring to the head 21, spindle 12, cap 10, heat-coil 14, ears 17 17, trigger 18, and linespring 8.

The operation of the device is as follows: /Vhen the current 4in the circuit under protection is normal, the device will remain in the condition shown in Figs. 1 and 2, with the circuit closed through it. When, however, the current becomes unduly strong, the heat-coil 14 generates or concentrates suicient heat to' melt or soften the solder 20, whereupon the trigger 18 is released and is swung outwardly by the line-spring 8. This movement of the trigger soon releases the line-spring 8 because of the passage of the upper end of said linespring from under the lower end of the trigger as the latter attains an inclined position in the opposite direction-that is, as shown by dotted lines in Fig. 2. When so released, the line-spring 8 opens the circuit by breaking the connection between itself and the trigger 18. The circuit is thereby opened and the passage of the`unduly-strong current is stopped. This constitutes and completes the operation of the device to open the circuit. It is of course necessary in apparatus of this sort to place the protective apparatus in condition for another operation after the trouble with the circuit by which the strong current was permitted tointrude has been removed. In protective apparatus of this general character it has heretofore been customary to replace or repair some part of the apparatus after each operation. By my present device herein shown this, however, is unnecessary. After the device has operated and the circuit been broken the solder 2O obviously cools off and assumes a hardened condition. The trigger 18 has been swung, however, from its original position to an oppositely-inclined position, as indicated by dotted lines in Figs. 2 and 4, so that when the solder hardens the trigger 18 is held by it in this new position as securely as it was held in the original positionwthat is to say, the device has been automatically resoldered or self-soldered. All that is necessary, therefore, is to turn the heat-cartridge 4 one hundred and eighty degrees on its longitudinal axis, by which reversal the trigger 18 is placed in a position corresponding, with reference to the line-spring 8, to its original position. The line-spring 8 is then reengaged with the lower end of the trigger, and the device is in normal position again, ready to operate a second time on the passage of an unduly strong current. On the passage of such a current the second time the device again operates as before, swinging the trigger bacl to its original position in the cartridge 4. Upon the solder again cooling' and hardening the heat-cartridge will be again turned on its axis one hundred and eighty degrees, bringing the trigger again into an inwardlyinclined position, after which it will be reengaged with the line-spring 8. In this way the device can be operated time after time practically without limit. Thus the need of repairs and replacement of parts and the consequent expense, annoyance, and trouble are avoided. It will also be seen that the selfsoldering heat-cartridge 4 is of very practicable and desirable construction in that it can be made in separate parts and very readily assembled and can be as easily taken apart to get access tothe interior.

In another application of mine, Serial No. 187,041, filed December29, 1908, I. have shown a construction of protector having certain of the broader features of the protector herein set forth, and in said other application I have included claims for such broader features.

It will be understood that changes and modifications can be made in the device herein set forth without departing from the spirit of my invention.

What I claim is* 1. In apparatus of the class specified, a heatcartridge, comprising a trigger pivoted between its ends and having both ends projecting to permit engagement of either end, and means whereby the trigger is normally held against movement but is permitted to move on the passage of an unduly strong current, substantially as described.

2. In apparatus of the class specified, a selfsoldering heat-cartridge, comprising a heatconcentrating member, a trigger pivoted bctween its ends and having its opposite ends projecting to permit either end to bc engaged, and means for holding the trigger normally against movement, said means being adapted to be affected by thc heat concentrated in said heatconcentrating member by an unduly strong current to permit movement of the trigger, and to resume its normal condition on the discontinuance of such concentration of heat, whereby the trigger is resecured after being actuated substantially as described.

8. In apparatus of the class specified, a selfsoldering heat-cartridge, comprising a trigger pivoted between its ends and having' both of its ends adapted to be engaged, a small quantity of material normally hard but softenable on a moderate excess of heat, said material when hard holding said trigger against movement and means for concentrating heat upon the passage of an unduly strong current to IOO ' ed to concentrate heat to melt or soften the solder on the passage of an unduly strong current, and a head forming a means for engaging the opposite end of the cartridge, substantially as described.

5. In apparatus of the class specitied, a heatcartridge comprising a tubular member made of insulating material, a cap or head attached to one end of said member, a core confined within said tubular member and provided with a heat-concentrating coil, a trigger attached to the end of said core and pivoted between its ends which are both adapted for engagement, and a small quantity of fusible or softenable material holding the trigger normally against movement, substantially as described.

6. In apparatus of the class specified, a heatcartridge comprising a tubular casing 7 of insulating material, a head 21 on one end of said tubular casing, a core within the casing, said core comprising a metallic cap 10 provided with a threaded shank 12 extending through the end of the casng' and holding the head 21 in position, a block 11 of insulating material, a bobbin 13 secured to the block 11 and provided with a coil of fine wire 14, ears 17 17 on the end of the bobbin 13, a trigger 18 located between the ears 17, 17 and pivoted at its middle point, the ends of said trigger eX- tending out beyond the ears 17, 17, and a small quantity of solder 20 holding the trigger 18 normally against movement` substantially as described.

7. In apparatus of the class specified, the combination with means for controlling the circuit, of a heat-cartridge comprising devices for engaging said circuit-controlling means, one of said devices being a trigger pivoted between its ends and having both of its ends projecting, and means whereby said trigger is held normally against movement but is released upon the passage of an unduly strong current, substantially as described.

8. In apparatus of the class specied, the combination with a pair of line-springs, of a heat-cartrid ge engaging said line-springs, said cartridge comprising a metallic head for en- Y gaging one of the line-springs, and a doubleended trigger pivoted .between its ends for engaging the other line-spring, a heat-concentrating member, and a small quantity of softenable material normally hard but adapted to be softened or fused by the heat concentrated in the heat-concentrating member by an unduly strong' current, said material when hard holding said trigger against movement substantially as described.

9. In apparatus of the class speciiied, the combination with a pair of line-springs, of a heat-cartridge comprising a metallic terminal or head, adapted to engage one of the linesprings, a double-ended trigger pivoted between its ends, a small quantity of solder holding the trigger normally against movement, a heat-coil, and a tubular casing of insulation inclosing the heat-coil and extended substantially between the metallic head and the trigger, substantially as described.

10. A heat-cartridge for electrical-circuit protectors having a bodily-removable core carrying a tine-wire heating-coil, and provided with a double trigger pivoted between its ends and having a solder connection with the cartridge.

11. A cartridge for electrical-circuit protectors having a bodily-removable core having a threaded connection for attaching it to the cartridge, said core being provided with a tine-wire heating-coil and also with a double trigger pivoted between its ends and soldered to the cartridge.

In witness whereof I hereunto subscribe my name this 16th day of June, A. D. 1904.

CHARLES A. ROLFE.

/Vitnesses:

A. MILLER BELFIELD, I. C. LEE. 

